Anaesthetics

Question 1

When is a jaw thrust the preferred airway manoeuvre

Answer 1

cervical spine injury

Question 2

oropharyngeal airway indications & pros

Answer 2

in an acute airway problem

as a bridging measure, before definitive airway

For v short procedures

pros: easy to insert & use. No paralysis required.

Question 3

laryngeal mask airway indications, pros & cons

Answer 3

Commonly used, esp for day surgery

not suitable for high-pressure ventilation

(sits in pharynx and aligns to cover airway)

pros: easy to insert
cons: poor control over gastric reflux

Question 4

Tracheostomy indications

Answer 4

Slow weaning from ETT

reduces work of breathing & dead space

percutaneous tracheostomy commonly used in ITU

cons: dries secretions, humidified air usually used in ITU

Question 5

Endotracheal tube indications

Answer 5

optimal control of airway once cuff inflated

used for long/ short-term ventilation

higher ventilation pressures can be used

Cons: errors may lead to oesophageal intubation - detected with capnography

Paralysis required

Question 6

ASA grades

Answer 6

1. (healthy)
   non-smoker, minimal alcohol
2. (mild systemic disease - i.e. no functional limitations)
   current smoker, social drinker, pregnancy, BMI 30-40, DM, HTN, mild lung disease
3. (severe systemic disease- functional limitations)
   poorly controlled DM, HTN, COPD, BMI>40, end stage renal disease & regular dialysis, MI or CVA hx, alcohol dependence , etc.
4. (severe disease constant threat to life)
   - recent (<3mo) MI or CVA, cardic ischemia, valve dysfunction, severely reduced EF, sepsis, ARD, ESRD w/out dialysis
5. (not suspected to survive without operation)
   - AAA, massive trauma, intra-cranial bleed w mass effect, multi organ failure
6. brain dead pt for organ harvest

Question 7

Propofol indication, MoA, features

Answer 7

IV

Indication & pros - commonly used for sedation induction & maintenance, in ITU for ventilated pts, high risk vomiting pts - some anti emetic properties, rapid metabolism

MoA- potentiates GABA

cons - moderate myocardial depression, pain on injection, hypotension

Question 8

Sodium thiopentone MoA, indication, cons

Answer 8

MoA- barbiturate, potentiates GABA

Indication- rapid sequence induction (v rapid onset) due to high lipid solubility

cons - laryngospasm, marked myocardial depression, metabolites build up, not for maintenance infusion, no analgesic effects

Question 9

ketamine indication, moa,

Answer 9

moa - NMDA receptor antagonist,

indication - induction of anaesthesia, strong analgesic properties, little myocardial depression (good for those who are haemodynamically unstable- i.e. trauma )

cons - may induce state of dissociative anaethesia resulting in nightmares

Question 10

Etomidate MoA, indication, cons

Answer 10

MoA - potentiates GABA

Indication - induction of anaesthesia, favourable cardiac safety profile w little haemodynamic instability

Cons - adrenal suppression (so not for Maintainance infusion!), post op vomiting is common, no analgesic properties

Question 11

Volatile liquid anaesthetic examples, indication, MoA, cons

Answer 11

isoflurane, desflurane, sevoflurane

indication - indication & Maintainance

MoA- unknown but combination of GABA, glycine & NDMA

cons- myocardial depression, malignant hyperthermia, (halothane = hepatotoxic)

Question 12

Nitrous oxide: examples, indication, cons

Answer 12

indication: Maintainance of anaesthesia and analgesia (e.g. labour)

adverse effects: may diffuse into gas filled area. Avoid in pneumothorax

Question 13

Cannula colour/ size order

Answer 13

biggest - Orange 14G (lava)
Grey 16G (rock)
Green 18G (grass)
Pink 20G (flower)
Blue 22G (sky)

Question 14

Local anesthetic toxicity can be treated with…

Answer 14

IV 20% lipid emulsion

Question 15

Malignant hypothermia causes

Answer 15

halothane
suxamethonium
other drugs: antipsychotics (neuroleptic malignant syndrome)

susceptibility inherited in autosomal dominant fashion

Question 16

malignant hyperthermia Ix and mx

Answer 16

(hyperpyrexia and muscle rigidity)

Investigations
CK raised
contracture tests with halothane and caffeine

Management
dantrolene - prevents Ca2+ release from the sarcoplasmic reticulum

Question 17

Deporalising neuromuscular blocker adverse effects & CI

Answer 17

(suxamethonium a.k.a succinylcholine)

hyperkalaemia, malignant hyperthermia, fasciculation and lack of acetylcholinesterase

increases IOP so CI in pts w penetrating eye injuries or acute narrow angle glaucoma

Question 18

nasopharyngeal airway indication & contraindication

Answer 18

ideal for seizure pts as you may not be able to put in OPA

CI - base of skull fractures

Question 19

causes of post op pyrexia

Answer 19

‘the 4 W’s’ (wind, water, wound, what did we do? (iatrogenic).

Early causes of post-op pyrexia (0-5 days) include:
- Physiological systemic inflammation (day1-2)
- - Pulmonary atelectasis (1-2)
- Urinary tract infection (d 3-5)
- Blood transfusion
- Cellulitis

Late causes (>5 days) include:
- Venous thromboembolism
- Pneumonia
- Wound infection
- Anastomotic leak
- iatrogenic (Abx or anaesthetic agents)

Question 20

Mx of postoperative ileus

Answer 20

check deranged potassium, magnesium and phosphate are not the cause

• nil-by-mouth initially, may progress to small sips of clear fluids
• nasogastric tube if vomiting
• IV fludis to maintain normovolaemia
  & additives to correct any electrolyte disturbances
• total parenteral nutrition
  occasionally for prolonged/severe cases

Question 21

Summary of diabetic control during surgery?

• metformin
• sulfonylurea
• DPP IV inhibitors
• GLP-1 analogues
• SGLT-2 inhibitors
• Once daily insulin (Lantus, Levemir)
• twice daily biphasic or ultra-long acting insulins

Answer 21

If long fasting period w more than 1 missed meal/ poor diabetic control = variable rate IV insulin infusion

Otherwise, just change normal regime:

metformin- if taken TDS, omit lunchtime dose. otherwise normal.

sulfonylurea - omit on day of surgery. unless taking BD w morning surgery - only omit morning dose.

DPP IV inhibitors , GLP-1 analogues , SGLT-2 inhibitors -> take as normal

Once daily insulins (e.g. Lantus, Levemir) - reduce doses by 20% on the day before & day of surgery

Twice daily Biphasic or ultra-long acting insulins (e.g. Novomix 30, Humulin M3) - half morning dose, evening dose unchanged

Question 22

which nerve is most likely to be injured in posterior triangle lymph node biopsy

Answer 22

Accessory

Question 23

which nerve is most likely to be injured in Posterior approach to hip

Answer 23

Sciatic

Question 24

which nerve is most likely to be injured in

Question 25

which nerve is most likely to be injured when Legs in Lloyd Davies position

Answer 25

common perineal

Question 26

which nerve is most likely to be injured in Axillary node clearance

Answer 26

Long thoracic

Question 27

which nerve is most likely to be injured in Pelvic cancer surgery

Answer 27

Pelvic autonomic nerves

Question 28

which nerve is most likely to be injured in thyroid surgery

Answer 28

Recurrent laryngeal nerves

Question 29

which nerve is most likely to be injured in carotid endarterectomy

Answer 29

Hypoglossal nerve

Question 30

which nerve is most likely to be injured during upper limb fracture repair

Answer 30

Ulnar and median nerves

Question 31

WHO checklist 3 phases of an operation

Answer 31

1) Before the induction of anaesthesia (sign in)
2) Before the incision of the skin (time out)
3) Before the patient leaves the operating room (sign out)

Question 32

Before the induction of anaesthesia, the following must have been checked:

Answer 32

• Patient has confirmed: Site, identity, procedure, consent
• Site is marked
• Anaesthesia safety check completed
• Pulse oximeter on & functioning
• known allergy?
• difficult airway/aspiration risk?
• risk of > 500ml blood loss (7ml/kg in children)?

Question 33

COCP changes before surgery?

Answer 33

Advise women to stop taking their combined oral contraceptive pill/hormone replacement therapy 4 weeks before surgery